In a variety of applications and operating environments, it may be desirable to provide protection against incident radiation and/or aero-thermal heating. In the field of optics, with respect to ambient radiation, an optical device with a given field of view may be capable of detecting radiation from a variety of sources. In certain cases, some radiation sources may obstruct detection of other radiation sources. This obstruction may reduce the utility of specific optical systems with regard to analysis of particular radiation sources. For these systems, it may be desirable to shield the system for radiation in order to improve the utility of the optical device.
With respect to aero-thermal protection, some optical devices may be configured for use in conditions likely to produce aero-thermal heating, as in the case of aerial projectiles. If this heating is transferred to an optical device, it may impair use of the device. In such situations, it may be desirable to shield the system from aero-thermal heating in order to improve the utility of the optical device.
In certain practical applications, some projectile systems may be configured to jettison a nose cone at a particular stage in their operation. Prior to being jettisoned, the nose cone may substantially constrain the geometry of an occlusive and/or aero-thermal protecting collar. When the nose cone is jettisoned, such constraints are generally irrelevant.
Various conventional systems have been proposed to provide radiation occlusion and/or aero-thermal protection. A representative system uses expandable welded bellows coupled to the optical system. When extended, the bellows take the shape of a substantially cylindrical, substantially hollow collar surrounding the optical device and having a principal axis substantially coincident with that of the optical device. The expanded bellows may be configured to prevent obstructive radiation from interfering with radiation sources inside the field of view of the optical system. The expanded bellows may also be configured to provide the optical device with aero-thermal protection. When a bellows system is configured for one or both of these features, the utility of the optical system is generally increased; however, problems with the bellows system include a high number of moving parts (along with attendant heightened probability of failure), a relatively high mass, a corresponding complexity of the translation calculation when employed in a projectile, a relatively low stiffness, and a tendency to deform.
Accordingly, there is a need for an extendable protective device that may be used to provide radiation occlusion and/or shielding against aero-thermal heating that is both lightweight and mechanically simplified. Additionally, there is a need for an extendable protective device that provides a low probability of failure and that addresses other deficiencies associated with the conventional art.